Many industrial and consumer products require the process of heat transfer for continuous and un-interrupted working. Convective heat transfer can be enhanced passively by changing flow geometry, boundary conditions, or by enhancing thermal conductivity of the heat transfer fluid. As extended surface technology has already been adapted to its limits in the design of thermal management systems, technologies with the potential to improve a fluid's thermal properties, such as conductivity, are of great importance.
Scientists and engineers have been working for decades to develop more efficient heat transfer fluids for use in car motors and industrial equipments. Improved oils and coolants would make possible more efficient machines and better engines. Such machines and engines would be smaller and cheaper, and their lower fuel demands and emissions would do less damage to the environment. More efficient heat transfer fluids may also solve a number of problems plaguing the heating, ventilation and air conditioning (HVAC) industry, improve the efficiency of high-heat flux devices like supercomputers, and provide new cancer treatment techniques. Many such requirements and continuous research has led to the development of nanofluids for heat transfer. Usual heat transfer fluids, also referred to as base fluids, with suspended ultra fine particles of nanometer size are named as nanofluids.
Nanofluids are typically engineered by suspending nano particles, preferably those possessing higher thermal conductivity, such as carbon, metal and metal oxides, with average sizes below 100 nanometer (nm) in traditional heat transfer fluids, such as water, oil, and ethylene glycol. Nanofluids form a new class of nanotechnology based heat transfer fluids that are expected to exhibit thermal properties superior to those of their host fluids or conventional particle fluid suspensions. Nanofluids prepared conventionally for the purpose of heat transfer applications have only been prepared in small quantities and at lab scale with limited stability and for trial purposes, but are not yet commercially available.